Mulch is sold by the cubic yard. A cubic yard of mulch is three feet wide, three feet deep and three feet tall. One yard is basically the amount of one scoop with a small skid steer bulldozer. Two yards is the amount that will fit in a full size pickup bed if the mulch is flush with the top of the bed rails. 13.5 regular bags of mulch equals one cubic yard.
A cubic yard covers 325 square feet of mulch beds with one inch of mulch. Try the free mulch calculator tool at the bottom of this page to estimate your project costs and mulch requirements.